Time for a more accurate estimate. The aerobic machines give a semi-accurate account of Calories burned, but the resistance machines are more problematic. I spend 22 minutes aerobically exercising and around 28 minutes on the resistance machines and was assuming roughly equal energy expenditure.

"The exact number of calories burned during strength training workouts depends on intensity, time and your body composition. According to the Harvard Medical School, on average, caloric burn ranges from 90 calories per hour of moderate training by a 125-pound person to up to 266 calories per hour of vigorous effort by a 185-pound person."